Retention of heavy metals by carboxyl functional groups of biochars in small arms range soil.
Retention of heavy metals by carboxyl functional groups of biochars in small arms range soil.
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DOI：
10.1021/jf2047898
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发表时间：
2012-02
影响因子：
6.1
通讯作者：
Minori Uchimiya;D. Bannon;L. Wartelle
中科院分区：
文献类型：
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作者：
Minori Uchimiya;D. Bannon;L. Wartelle
生物质炭对重金属的长期稳定效果取决于其在土壤中的吸附性能和迁移能力。为了解羧基在重金属稳定化中的作用，采用浓H2SO 4/HNO 3和30%HNO3对低O/C比（0.04-0.06）、高固定碳含量（~80%干重）的棉籽船体和亚麻木屑生物炭进行了水蒸气活化处理。氧化和未氧化的生物炭的O/C比，总酸度，pH值，水分，灰分，挥发分，固定碳含量，Brunauer-Emmett-Teller表面积，和衰减全反射傅里叶变换红外光谱特征进行了表征。在桑迪、微酸性（pH 6.27）重金属污染的轻武器靶场土壤部分（<250 μm）上改良表征的生物炭（2%、5%、10%和20%，以克生物炭/克土壤计），该土壤部分具有低总有机碳（0.518%）和低阳离子交换容量（0.95 cmol（c）kg（-1））。富含羧基官能团的氧化生物炭表现出显着更大的铅，铜，锌的稳定能力相比，未氧化的生物炭，特别是在pH 4.9的醋酸盐缓冲液（标准溶液的毒性特征浸出程序）。相反，只有氧化的生物炭引起Sb的解吸，表明羧基官能团对阴离子和阳离子的溶解度的抵消影响。研究结果表明，选择合适的生物炭氧化剂，可制备出富含羧基官能团的柠檬酸型生物炭，用于污染土壤中重金属的长期稳定。
Long-term effectiveness of biochar for heavy metal stabilization depends upon biochar's sorptive property and recalcitrance in soil. To understand the role of carboxyl functional groups on heavy metal stabilization, cottonseed hull biochar and flax shive steam-activated biochar having a low O/C ratio (0.04-0.06) and high fixed carbon content (~80% dry weight basis) were oxidized using concentrated H(2)SO(4)/HNO(3) and 30% HNO(3). Oxidized and unoxidized biochars were characterized for O/C ratio, total acidity, pH, moisture, ash, volatile matter, and fixed carbon contents, Brunauer-Emmett-Teller surface area, and attenuated total reflectance Fourier transform infrared spectral features. Characterized biochars were amended (2%, 5%, 10%, and 20% in grams of biochar per gram of soil) on a sandy, slightly acidic (pH 6.27) heavy metal contaminated small arms range soil fraction (<250 μm) having low total organic carbon (0.518%) and low cation exchange capacity (0.95 cmol(c) kg(-1)). Oxidized biochars rich in carboxyl functional groups exhibited significantly greater Pb, Cu, and Zn stabilization ability compared to unoxidized biochars, especially in pH 4.9 acetate buffer (standard solution for the toxicity characteristic leaching procedure). Oppositely, only oxidized biochars caused desorption of Sb, indicating a counteracting impact of carboxyl functional groups on the solubility of anions and cations. The results suggested that appropriate selection of biochar oxidant will produce recalcitrant biochars rich in carboxyl functional groups for a long-term heavy metal stabilization strategy in contaminated soils.